Booster device for inclusion in the exhaust system of an internal combustion engine



Oct. 11, 1960 v v H. FARTHING 955,670

2 BOOSTER DEVICE FOR INCLUSION IN THE EXHAUST SYSTEM OF AN INTERNALCOMBUSTION ENGINE Filed Nov. 28, 1956 11* FIG. I

N VE N TOR MWNOA/ fr. 545 TH/A/q Vernon Hilton Farthing, 329 Tower Bldg,Water St., Liverpool 3, England F led NOY- 1 Claim. (Cl. 181-43)Thisinvention is for improvements in or relating to a silencer accessoryor a silencer for incorporation in the exhaust system of an internalcombustion engine.

It is an object of the invention to provide a silencer accessory or asilencer for an exhaust system which is adapted to reduce the backpressure effect on the engine, that is to say will prevent or reduce themomentary back pressure effect by tending to prevent substantially backfiow surge effects from the atmospheric end of the exhaust pipe up tothe port itself. It is a further object of the invention to provide asilencer accessory or silencer which will give a positive extractioneffect and cooling effect upon the exhaust system.

Conventional straight-through exhaust systems, whilst apparently givinga low mean back pressure, do not help the porting characteristics of theengine. In the conventional straight-through silencer system the highpressure peak of the exhaust gas wave-form, corresponding to the periodof opening of the exhaust valve, is followed by a partial vacuum whichcauses the outside air to form a momentary back pressure effect at theexhaust valve or port against the free exit of the next high pressurepeak. This can have a most serious effect on engine performance andefiiciency and necessitates careful design of the exhaust pipe system ifthis adverse effect is to be reduced.

According to the present invention there is provided an accessory forincorporation in a gas exhaust system of an internal combustion enginecomprising a casing having an inlet at one end for the exhaust gases, atleast two outlets at the other end, and an inlet for the passage intothe casing of external air, said casing providing a substantiallyunobstructed passage for the flow of exhaust gases and air from saidinlets to said outlets and the inlet for exhaust gases being inalignment with one of said outlets and said inlet for external air beingpositioned so that air is directed into and through the casing towardsthe other outlet in substantially the same direction as the exhaustgases are directed into and through said casing. In preferredembodiments of the invention the inlet for exhaust gases is in alignmentwith one outlet and the inlet for air is in alignment with the otheroutlet.

By the arrangement just described air entering the casing fills up thespaces between the exhaust pulses so that pulsation effects areeliminated. By providing separate outlets excess air not required forthe purpose just set forth is carried away completely separate from theexhaust and does not interfere therewith.

The invention will be further described by way of example with referenceto the accompanying drawings, wherein: 65

Figure 1 is a sectional plan view of a silencer accessory in accordancewith the invention,

Figure 2 is a cross-section on the line IIII of Figure 1, and

Figure 3 is an end elevation.

The accessory shown in Figures 1, 2 and 3 of the drawing comprises acasing 10 of oval or like cross section although it could be round or ofother section if desired. One end of the casing is provided with a shortlength of pipe 11 by which it can be connected to the exhaust end of thesomewhat shortened normal silencer outlet pipe of a motor vehicle. Atits opposite end the casing 10 is provided with twin outlet pipes 12 and13. The outlet pipe 12 is in axial alignment with the inlet pipe 11. Atthe inlet end of the casing 10 an opening 14 is provided which is fittedwith a convergent nozzle or jet 15 and serves for the introduction intothe casing 10 of atmospheric air, the motion of the vehicle promotingthis flow of air. It will be noted that the jet 15 is in axial alignmentwith the outlet pipe 13.

In the corrector unit or accessory above described, which corrector unitforms an auxiliary or accessory to the normal exhaust system of themotor vehicle, the air flow, due to the motion of the vehicle andcontrolled by the nozzle structure, prevents or reduces the partialvacuum effect, the inertia of the air in the casing and constant coldair flow tending substantially to prevent the back flow surge effectfrom the atmospheric end of the exhaust pipe back to the exhaust portitself.

Given appropriate physical dimensions and speed of vehicle or air flow,the accessory or corrector unit can be extended so,as to act as anextractor unit for the exhaust gases which of course further extends itsfunction and promotes its efficiency.

Although designed principally for use with a straightthrough type ofsilencer the accessory above described is also of benefit in other typesof silencer Where it smooths out remaining pulsations and minimisesstanding wave effects thus giving the absolute minimum of back pressurein the Whole system.

Apart from increasing engine performance and efficiency the accessoryaccording to the present invention increases the efiiciency of thesilencer system and gives the pleasing and desirable appearance of apartial twin exhaust system without the cost and difficulty of fittingand manufacturing the conventional type of twin exhaust system.

In some cases if a high frequency absorber section is added theaccessory according to the present invention may be located before,instead of behind, the normal silencer of the exhaust system.

For some applications a blower may be provided to supply external air tothe casing of the accessory.

An accessory such as previously described can be adapted to constitute amain silencer by virtue of the fact that the cold air substantiallycools the exhaust gas and reduces its pressure and amplitude of waveform by its mixing and yet under appropriate conditions of speed and jetdesign will assist in the evacuation of the exhaust gas and thus producesilencing substantially equivalent to that of a conventional silencerbut with reduced size and reduced blockaging troubles and above all verymuch reduced static back pressure and substantial elimination ofpulsating effects of standing waves tending to upset the portingcharacteristics of the engine.

A silencer according to the present invention is applicable to anyvehicle (eg. a motor car or ship) or in fact any form of engine whereingas flow may be assisted by utilisation of the movement of an outsideair stream relative to the silencer, such air flow being promoted by themotion of a vehicle on which the silencer is fitted, by the provision ofan air pump or blower or by the flow or chimney effect of the exhaustgases themselves.

I claim:

An accessory for reducing pulsation effects and consequent back pressurein the exhaust gas system of an internal combustion engine comprising anelongate casing having an inlet at one end for connection to the exhaustsystem of an internal combustion engine and through which inlet exhaustgases are discharged into the casing, said inlet discharging exhaustgases directly into the easing adjacent said one end of the same, anexhaust gas outlet at the opposite end of the casing in axial alignmentwith said inlet, the openings of said inlet and outlet being spacedapart a distance substantially equal to the length of the casing and theinterior of the casing being free and unobstructed therebetween, an airinlet at said one end of the casing spaced to one side of said exhaustgas inlet, a second outlet at said opposite end of the casing in axialalignment with said air inlet, the openings of the air inlet and secondoutlet being spaced apart a substantial distance and the interior of thecasing being free and unobstructed therebetween and with the portion ofthe casing between the exhaust gas inlet and exhaust gas outlet beingfreely communicated with the portion of the casing between the air inletand the second outlet, whereby pulsations efiected by 'the cyclic andperiodic discharge of exhaust gases into the casing through said gasinlet will be smoothed out by alternate inflow of air through said airinlet to obviate back pressure within the casing and Within the exhaustsystem of the associated internal combustion engine.

References Cited in the file of this patent UNITED STATES PATENTS756,203 Barthel Apr. 5, 1904 1,382,690 Stokes June 28, 1921 2,155,052Byland Apr. 18, 1939 2,162,683 Tobin June 13, 1939 2,229,576 Kirby Jan.21, 1941 2,356,782 Muller Aug. 29, 1944 2,386,305 Flickinger Oct. 9,1945 FOREIGN PATENTS 804,213 France July 27, 1936 62,724 Norway July 22,1940

